In early 2019, many people installing or updating Blue Iris 4 began seeing this error message when trying to start Blue Iris:
The application was unable to start correctly (0xc000007b). Click OK to close the application.
The solution is to install Visual C++ Redistributable Packages for Visual Studio 2013
Microsoft offers 3 downloads for this, and which one you need depends on if you are installing 64-bit Blue Iris (x64) or 32-bit (x86).